The present invention relates to cable television and particularly to a technique whereby a cable subscriber can send a request via telephone to the cable operator to receive only a selected cable program. This is known as an "impulse pay per view" system.
The preferred embodiment of the present invention is compatible with one-way addressable CATV systems. Prior to describing the invention, it will be useful to have a rudimentary understanding of a typical one-way addressable CATV system. In use, a cable operator at a "headend" station receives signals via satellite, microwave, and super trunks, encodes the signals, modulates them, and provides them to the cable plant. The cable plant is a distribution network typically carrying up to 80 channels or more over a distance of up to 20 miles or so to various subscribers. Each of the cable subscribers is provided with a one-way addressable converter (also called a decoder) which is connected to the cable and to a television receiver or monitor. The basic function of the converter is to interface the cable signals with the subscriber according to authorization codes received from the headend. The subscriber will select a channel containing a program desired to be viewed. The converter will determine whether that channel or program on the channel is authorized for viewing by the subscriber. If so, the converter descrambles the selected signal provided by the cable operator and provides a descrambled signal to the television receiver or monitor. The scrambling may, for example, be done by sync suppression wherein sync information is randomly suppressed, as well as video inversion.
To achieve the foregoing system, use may be made of the vertical blanking interval, e.g. line numbers 10, 11, 12 and 13, or an out-of-band data channel during which information can be transmitted by the headend station to the subscribers or any selected subscriber. Each converter has a respective unique address code illustratively having 20 binary bits so that over one million subscribers can be individually addressed by the headend. Additionally, each converter typically includes a random access memory (RAM) which is capable of storing 20 bits, for example. Each of the stored bits is representative of a service or channel which may be subscribed to. Typically, at installation, the RAM is loaded with all zero bits. When the subscriber chooses the services he wants, that information will be entered as data in a subscriber data base. The subscriber data base is accessed by a system controller at the headend station which is capable of addressing any or all of the converters in the field. The system controller also communicates with a billing and management computer.
More particularly, in this example the system controller transmits a selected 20 bit address code (sometimes referred to as an "identification code") followed by an associated authorization code using each of line numbers 10, 11, and/or 12 in the vertical blanking interval. Each converter receives the 20 bit address code, but only one converter will decode it as matching its own unique address. Following the transmitted 20 bit address code are the five bits of the authorization code. These five authorization bits will be loaded into a proper location in the RAM, the location having been determined by information from line 13 in the prior field. The RAM in the converter will illustratively contain 20 bits arranged in four groups which may be called row A, row B, row C, and row D. Illustratively, the five bit authorization code will be loaded into one of the rows of the RAM. Line number 13 of the vertical interval is used to transmit a "program tag," a "market code," and further information to the converters in the field. The market code is used to prevent a converter from being taken from one cable market to another market. The transmitted program tag is used to identify a particular channel or program and is compared in the addressed converter with the stored authorization bits to establish whether that converter is authorized to descramble the corresponding program material. Illustratively, this is done by performing a logical AND operation between the 5 bit program tag transmitted on line 13 of the channel which has been selected by the subscriber with the content of a selected row of the RAM. The result of this logical operation will indicate to the converter whether the selected channel or program on the channel has been authorized to be descrambled by the converter. It will be appreciated that each of the channels transmitted by the cable operator has its own respective program tag. This particular system has exceptional versatility in that the contents of the RAM at any subscriber's converter can be changed instantly via the system controller through the transmission of the appropriate address code during the vertical blanking interval followed by updated information for storage in the RAM. Moreover, there can be tiers of authorization wherein various programs on a given channel will be authorized for some subscribers but not for others, depending on the service to which they have subscribed. For further information about one such addressable system, refer to Ensinger and Hendrickson U.S. Pat. No. 4,460,992, whose disclosure is hereby incorporated, which patent is owned by Zenith Electronics Corp.
To date, the market penetration of cable systems has been on the order of only 50 percent. Some television owners prefer not to pay the monthly charges for cable service to receive one or more of the packages or services provided by the cable operator. These non-subscribers, however, may be willing to pay the cable operator for only an occasional program. Such type of service is called "pay per view." In order to achieve this and to provide control over billing, the cable operator must have information regarding what programs are desired by various subscribers. In an addressable CATV system of the type described above, for example, a particular subscriber's converter may be updated so that it will descramble a given program--once it is determined that the subscriber is wlling to pay for that program. This can be done by having the subscriber telephone the cable operator in advance of the program to be purchased, mail a postcard, or communicate by some other means.
The problem with this type of service, however, is that it precludes impulse purchases and simultaneous response from the time the pay-per-view subscriber determines he wishes to purchase a particular program and the time it is actually viewed by him. It would be considerably more advantageous to permit a subscriber to obtain immediate results by, for example, pushing a button. This would alert the cable operator to a request for service. The system controller at the headend station immediately would change the contents of the RAM at that subscriber's converter to permit the selected program to be descrambled. This is called "impulse pay per view" (IPPV) service.
The problem facing the industry is how to provide a system permitting IPPV service. In 1975, the Federal Communications Commission mandated that all cable systems being installed would be required to have two-way communications capability. This would permit interaction between the subscriber and the headend station. To date, about 20 percent of installed systems are capable of two-way communications, and of these only about one-half have active two-way communication. With two-way communication, the subscriber can use his home terminal or other unit to communicate with the headend station and achieve IPPV. The problem, however, resides in providing a mechanism for other subscribers served by one-way cable systems, which constitute the vast majority to have IPPV service.
For cable subscribers without two-way cable systems, a hybrid system is required for impulse pay per view service. This involves a telephone request by a subscriber for a PPV cable event followed by delivery from the cable operator headend station to the individual subscriber of a new authorization level permitting the PPV cable event to be descrambled.
The problem with hybrid systems using the telephone is substantial. The telephone system in a given city or community includes one or more central offices, each communicating with up to about 50,000 telephone subscribers. Each of the several central offices communicates with the others by trank cables. The headend station of the cable operator will be located within a region serviced by one central office. When cable subscribers telephone for pay per view service, their telephone central offices will route all of the telephone calls to the one central office servicing the headend station. Too many telephone requests at the same time to the cable operator can cause the telephone central office to "crash" due to excessive requests for physical telephone connections between numerous telephone subscribers and a single cable operator headend station. This problem is common to all hybrid systems, whether a manual telephone system or an automatic dialing system is used.
Further problems attend manual call-in systems and auto-dialing systems. The manual call-in systems are labor intensive, require long processing and holding time, have limited capacity, are not impulse in nature, and have lower penetration. They also involve possible human error. Auto-dialing systems have an advantage over manual systems, except that there is the additional expense of in-home installation of the automatic dialer.
To avoid overloading on the telephone system, one solution to providing IPPV service for one-way addressable cable systems would be to refrain from making physical telephone connections between the cable subscribers and the headend station through the various central offices. To achieve this, a new system based on automatic number identification passing referred to as "ANI passing" has been developed. ANI passing is an upgrade achieved by adding software to some central offices or by adding hardware to others, depending on their existing capabilities. In ANI passing, the central office of the telephone company will collect information based on each subscriber telephone call and pass it on to other equipment.
Thus, when a cable subscriber intends to make an IPPV request and picks up his telephone (takes it "off-hook"), a dial tone is issued to the subscriber's premises by the telephone company, and the telephone number is automatically identified, as customary within the telephone company. Now the cable subscriber can enter information using the telephone. Typically, to place a phone call, seven digits (or ten, if an area code is needed) are entered. To use ANI passing, however, some prescribed sequence of digits is used. This can take vertically any form. For example, the subscriber may enter "*85" or any other prescribed NNX number (exchange number) and then some number of digits, such as four further digits. In general, however, the total number of digits need not be seven, so long as some prescribed subscriber-entered information alerts the telephone company central office not to make a physical connection between the telephone subscriber and whatever location is identified by the code which follows the reserved block of codes which follows the NNX (or *85 signal). After dialing the NNX number, for example, the cable subscriber will provide further information on the telephone by sending illustratively four digits. Hence the telephone transmission to the central office may take the following form: NNX-YVVZ. In this illustrative example, the code represented by NNX activates the ANI passing system at the central office. The remaining four digits YVVZ identify what the subscriber wants to do. Illustratively, the Y digit is used to identify the cable company. In any given metropolitan area, there will be fewer than ten different cable operators, so the one digit (Y) will be able to identify the cable operator uniquely. Illustratively, the next two digits represented by VV identify the event or cable television program which the cable subscriber wishes to purchase. Next, the Z digit may represent a password which is useful for security purposes. For example, within a given household where a cable television system has been installed, parents may, through the use of a password, prevent access by children to certain types of pay per view programming. Alternatively, the Z digit can be used for other purposes. In using *85, five digits can be entered by the cable subscriber to his telephone, for a total of, for example, seven digits preceded by one special character. One of the digits may identify the cable company, two of the digits may identify the cable event to be purchased (or canceled), and two digits may be used as a password. It will be understood that these are purely illustrative, and that wide variation can occur.
As mentioned, the NNX or *85 message tells the telephone central office that it need not make a physical connection. This avoids overburdening the telephone plant. In response to receiving such an ANI transmission, the receiving telephone central office will collect and store data. Then, it will communicate by the system of the present invention with the cable headend station which has been .-+.telephoned" and provide it with various information, including the telephone number of the cable subscribers who called, the user entered data, and various other information. In an area served by plural cable companies, the equipment at the telephone company central offices will send data, using the present invention, to the plural cable companies.
The object of the present invention is to provide a system which will receive information from the telephone company central offices and implement the impulse pay per view requests by cable subscribers in a satisfactory manner.
A related object of the invention is to provide a system having the ability to receive data from the telephone companies as fast as the information can be provided using the ANI passing systems.
Another object of the present invention is to permit the authorizations of the subscribers to be checked in real time.
A further object is to translate the telephone number of the cable subscriber (provided by the telephone company) into a cable subscriber code at a fast rate.